1 files changed, 281 insertions, 0 deletions
diff --git a/gearboy/src/audio/Multi_Buffer.cpp b/gearboy/src/audio/Multi_Buffer.cpp
new file mode 100644
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+++ b/gearboy/src/audio/Multi_Buffer.cpp
@@ -0,0 +1,281 @@
+// Blip_Buffer 0.4.1. http://www.slack.net/~ant/
+
+#include "Multi_Buffer.h"
+
+/* Copyright (C) 2003-2007 Shay Green. This module is free software; you
+can redistribute it and/or modify it under the terms of the GNU Lesser
+General Public License as published by the Free Software Foundation; either
+version 2.1 of the License, or (at your option) any later version. This
+module is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
+details. You should have received a copy of the GNU Lesser General Public
+License along with this module; if not, write to the Free Software Foundation,
+Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
+
+#include "blargg_source.h"
+
+#ifdef BLARGG_ENABLE_OPTIMIZER
+	#include BLARGG_ENABLE_OPTIMIZER
+#endif
+
+Multi_Buffer::Multi_Buffer( int spf ) : samples_per_frame_( spf )
+{
+	length_                 = 0;
+	sample_rate_            = 0;
+	channels_changed_count_ = 1;
+	channel_types_          = 0;
+	channel_count_          = 0;
+	immediate_removal_      = true;
+}
+
+Multi_Buffer::channel_t Multi_Buffer::channel( int /*index*/ )
+{
+	static channel_t const ch = { 0, 0, 0 };
+	return ch;
+}
+
+// Silent_Buffer
+
+Silent_Buffer::Silent_Buffer() : Multi_Buffer( 1 ) // 0 channels would probably confuse
+{
+	// TODO: better to use empty Blip_Buffer so caller never has to check for NULL?
+	chan.left   = 0;
+	chan.center = 0;
+	chan.right  = 0;
+}
+
+// Mono_Buffer
+
+Mono_Buffer::Mono_Buffer() : Multi_Buffer( 1 )
+{
+	chan.center = &buf;
+	chan.left   = &buf;
+	chan.right  = &buf;
+}
+
+Mono_Buffer::~Mono_Buffer() { }
+
+blargg_err_t Mono_Buffer::set_sample_rate( long rate, int msec )
+{
+	RETURN_ERR( buf.set_sample_rate( rate, msec ) );
+	return Multi_Buffer::set_sample_rate( buf.sample_rate(), buf.length() );
+}
+
+
+// Tracked_Blip_Buffer
+
+Tracked_Blip_Buffer::Tracked_Blip_Buffer()
+{
+	last_non_silence = 0;
+}
+
+void Tracked_Blip_Buffer::clear()
+{
+	last_non_silence = 0;
+	Blip_Buffer::clear();
+}
+
+void Tracked_Blip_Buffer::end_frame( blip_time_t t )
+{
+	Blip_Buffer::end_frame( t );
+	if ( clear_modified() )
+		last_non_silence = (int)samples_avail() + blip_buffer_extra_;
+}
+
+blip_ulong Tracked_Blip_Buffer::non_silent() const
+{
+	return last_non_silence | unsettled();
+}
+
+inline void Tracked_Blip_Buffer::remove_( long n )
+{
+	if ( (last_non_silence -= n) < 0 )
+		last_non_silence = 0;
+}
+
+void Tracked_Blip_Buffer::remove_silence( long n )
+{
+	remove_( n );
+	Blip_Buffer::remove_silence( n );
+}
+
+void Tracked_Blip_Buffer::remove_samples( long n )
+{
+	remove_( n );
+	Blip_Buffer::remove_samples( n );
+}
+
+void Tracked_Blip_Buffer::remove_all_samples()
+{
+	long avail = samples_avail();
+	if ( !non_silent() )
+		remove_silence( avail );
+	else
+		remove_samples( avail );
+}
+
+long Tracked_Blip_Buffer::read_samples( blip_sample_t* out, long count )
+{
+	count = Blip_Buffer::read_samples( out, count );
+	remove_( count );
+	return count;
+}
+
+// Stereo_Buffer
+
+int const stereo = 2;
+
+Stereo_Buffer::Stereo_Buffer() : Multi_Buffer( 2 )
+{
+	chan.center = mixer.bufs [2] = &bufs [2];
+	chan.left   = mixer.bufs [0] = &bufs [0];
+	chan.right  = mixer.bufs [1] = &bufs [1];
+	mixer.samples_read = 0;
+}
+
+Stereo_Buffer::~Stereo_Buffer() { }
+
+blargg_err_t Stereo_Buffer::set_sample_rate( long rate, int msec )
+{
+	mixer.samples_read = 0;
+	for ( int i = bufs_size; --i >= 0; )
+		RETURN_ERR( bufs [i].set_sample_rate( rate, msec ) );
+	return Multi_Buffer::set_sample_rate( bufs [0].sample_rate(), bufs [0].length() );
+}
+
+void Stereo_Buffer::clock_rate( long rate )
+{
+	for ( int i = bufs_size; --i >= 0; )
+		bufs [i].clock_rate( rate );
+}
+
+void Stereo_Buffer::bass_freq( int bass )
+{
+	for ( int i = bufs_size; --i >= 0; )
+		bufs [i].bass_freq( bass );
+}
+
+void Stereo_Buffer::clear()
+{
+	mixer.samples_read = 0;
+	for ( int i = bufs_size; --i >= 0; )
+		bufs [i].clear();
+}
+
+void Stereo_Buffer::end_frame( blip_time_t time )
+{
+	for ( int i = bufs_size; --i >= 0; )
+		bufs [i].end_frame( time );
+}
+
+long Stereo_Buffer::read_samples( blip_sample_t* out, long out_size )
+{
+	require( (out_size & 1) == 0 ); // must read an even number of samples
+	out_size = min( out_size, samples_avail() );
+
+	int pair_count = int (out_size >> 1);
+	if ( pair_count )
+	{
+		mixer.read_pairs( out, pair_count );
+
+		if ( samples_avail() <= 0 || immediate_removal() )
+		{
+			for ( int i = bufs_size; --i >= 0; )
+			{
+				buf_t& b = bufs [i];
+				// TODO: might miss non-silence settling since it checks END of last read
+				if ( !b.non_silent() )
+					b.remove_silence( mixer.samples_read );
+				else
+					b.remove_samples( mixer.samples_read );
+			}
+			mixer.samples_read = 0;
+		}
+	}
+	return out_size;
+}
+
+
+// Stereo_Mixer
+
+// mixers use a single index value to improve performance on register-challenged processors
+// offset goes from negative to zero
+
+void Stereo_Mixer::read_pairs( blip_sample_t* out, int count )
+{
+	// TODO: if caller never marks buffers as modified, uses mono
+	// except that buffer isn't cleared, so caller can encounter
+	// subtle problems and not realize the cause.
+	samples_read += count;
+	if ( bufs [0]->non_silent() | bufs [1]->non_silent() )
+		mix_stereo( out, count );
+	else
+		mix_mono( out, count );
+}
+
+void Stereo_Mixer::mix_mono( blip_sample_t* out_, int count )
+{
+	int const bass = BLIP_READER_BASS( *bufs [2] );
+	BLIP_READER_BEGIN( center, *bufs [2] );
+	BLIP_READER_ADJ_( center, samples_read );
+
+	typedef blip_sample_t stereo_blip_sample_t [stereo];
+	stereo_blip_sample_t* BLIP_RESTRICT out = (stereo_blip_sample_t*) out_ + count;
+	int offset = -count;
+	do
+	{
+		blargg_long s = BLIP_READER_READ( center );
+		BLIP_READER_NEXT_IDX_( center, bass, offset );
+		BLIP_CLAMP( s, s );
+
+		out [offset] [0] = (blip_sample_t) s;
+		out [offset] [1] = (blip_sample_t) s;
+	}
+	while ( ++offset );
+
+	BLIP_READER_END( center, *bufs [2] );
+}
+
+void Stereo_Mixer::mix_stereo( blip_sample_t* out_, int count )
+{
+	blip_sample_t* BLIP_RESTRICT out = out_ + count * stereo;
+
+	// do left + center and right + center separately to reduce register load
+	Tracked_Blip_Buffer* const* buf = &bufs [2];
+	while ( true ) // loop runs twice
+	{
+		--buf;
+		--out;
+
+		int const bass = BLIP_READER_BASS( *bufs [2] );
+		BLIP_READER_BEGIN( side,   **buf );
+		BLIP_READER_BEGIN( center, *bufs [2] );
+
+		BLIP_READER_ADJ_( side,   samples_read );
+		BLIP_READER_ADJ_( center, samples_read );
+
+		int offset = -count;
+		do
+		{
+			blargg_long s = BLIP_READER_READ_RAW( center ) + BLIP_READER_READ_RAW( side );
+			s >>= blip_sample_bits - 16;
+			BLIP_READER_NEXT_IDX_( side,   bass, offset );
+			BLIP_READER_NEXT_IDX_( center, bass, offset );
+			BLIP_CLAMP( s, s );
+
+			++offset; // before write since out is decremented to slightly before end
+			out [offset * stereo] = (blip_sample_t) s;
+		}
+		while ( offset );
+
+		BLIP_READER_END( side,   **buf );
+
+		if ( buf != bufs )
+			continue;
+
+		// only end center once
+		BLIP_READER_END( center, *bufs [2] );
+		break;
+	}
+}